Clear-rinsing agents with cationic polymers

ABSTRACT

PCT No. PCT/EP96/03724 Sec. 371 Date May 6, 1998 Sec. 102(e) Date May 6, 1998 PCT Filed Aug. 23, 1996 PCT Pub. No. WO97/09408 PCT Pub. Date Mar. 13, 1997A process for improving the soil release properties of dishwashing machine rinse aid compositions used to rinse dishware and remove starch-containing soils therefrom by adding to the compositions a cationic polymer containing monomer units corresponding to formula I: in which R1 is hydrogen or a methyl group, R2, R3 and R4 are the same or different and represent hydrogen or a C1-8 alk(en)yl group, R8 is a linear, cyclic or branched alkylene group containing 2 to 8 carbon atoms, and X represents a monofunctional anion or the 1/m part of an m-functional anion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the use of cationic polymers as soil releasecompounds in rinse aids for dishwashing machines.

Commercial rinse aids for dishwashing machines are mixtures oflow-foaming fatty alcohol polyethylene/polypropylene glycol ethers,solubilizers (for example cumene sulfonate), organic acids (for examplecitric acid) and solvents (for example ethanol). The function of theserinse aids is to influence the surface tension of the water in such away that the water is able to drain off the dishes in the form of a thincoherent film so that no droplets of water, streaks or films are leftbehind after the subsequent drying process. An overview of thecomposition of rinse aids and methods for testing their performance waspublished by W. Schirmer et al. in Tens. Surf. Det. 28, 313 (1991).

In machine dishwashing, it occasionally happens that firmly adheringsoils such as, for example, oat flakes and starch deposits are notcompletely removed during the cleaning process.

2. Discussion of Related Art

It is known from EP-A-0 167 382, EP-A-0 342 997 and DE-OS 26 16 404 thatcationic polymers can be added to dishwashing detergents to obtainstreak-free cleaning of the surfaces.

EP-A-0 167 382 describes liquid detergent compositions which may containcationic polymers as thickeners. Hydroxypropyl trimethyl ammonium guar,copolymers of aminoethyl methacrylate and acrylamide and copolymers ofdimethyl diallyl ammonium chloride and acrylamide are described asparticularly suitable cationic polymers.

EP-A-0 342 997 describes multipurpose cleaners which may containcationic polymers, more particularly polymers containing imino groups.

DE-OS 26 16 404 describes glass cleaners containing cationic cellulosederivatives. The addition of the cationic cellulose derivatives improvesdrainage of the water so that no streaks are left behind on the cleanedglass.

EP-A-0 467 472 describes hard surface cleaners containing cationichomopolymers and/or copolymers as so-called soil release polymers. Thesepolymers contain quaternized ammonium alkyl methacrylate groups asmonomer units. These compounds are used to finish the surfaces in such away that the soils are easier to remove the next time the surfaces arecleaned.

The documents cited above disclose the use of cationic polymers incleaning formulations. There is nothing in any of these documents toindicate how it is possible in machine dishwashing to facilitate theremoval of obstinate soils, for example starch-containing soils.

The problem addressed by the present invention was to provide a rinseaid which would enable firmly adhering soils, such as oat flakes andother starch deposits, to be readily removed from the dishes insubsequent cleaning cycles.

DESCRIPTION OF THE INVENTION

The present invention relates to the use of cationic polymers selectedfrom cationic polymers of copolymers of monomers, such as trialkylammonium alkyl (meth)acrylate or acrylamide; dialkyl diallyl diammoniumsalts; polymer-analog reaction products of ethers or esters ofpolysaccharides containing ammonium side groups, more particularly guar,cellulose and starch derivatives; polyadducts of ethylene oxidecontaining ammonium groups; quaternary ethylene imine polymers andpolyesters and polyamides containing quaternary side groups as soilrelease compounds in rinse aids for dishwashing machines.

It has surprisingly been found that, if soil release compounds are addedto the rinse aid in machine dishwashing, firmly adhering and oftencritical soils, for example starch-containing soils, can be completelyremoved in the next dishwashing cycle. These soils can be removedwithout any need for additional manual cleaning of the dishes.

Suitable cationic polymers are, in particular, water-solublehomopolymers or copolymers containing monomer units corresponding toformula I: ##STR2## in which

R¹ is hydrogen or a methyl group and

R², R³ and R⁴ may be the same or different and represent hydrogen or aC₁₋₈ alk(en)yl group, R⁸ is a linear, cyclic or branched alkylene groupcontaining 2 to 8 carbon atoms and

X represents a monofunctional anion or the 1/m part of an m-functionalanion.

Other suitable polymers are those which contain monomer unitscorresponding to formula II: ##STR3## in which R⁵ to R⁷ and R⁹ representlower C₁₋₄ alkyl groups, R⁸ is an alkylene group containing 2 to 8carbon atoms and Y is a monofunctional anion or the 1/n part of ann-functional anion,

as described in European patent application 467 472.

The anions in formulae I and II may be, for example, halide ions, suchas chloride or bromide, SO₄ ²⁻ or CH₃ SO₄ ⁻.

The polymers preferably used may contain 40 mole-% to 100 mole-% of themonomer units corresponding to formula I or II. The percentage ofmonomer units corresponding to formula I should preferably be no lowerthan 40 mole-% because otherwise the polymers would not have sufficientsolubility in water. Besides the monomer units corresponding to formulaI, unsaturated monocarboxylic acids, such as acrylic acid, methacrylicacid, crotonic acid and the like, olefins, such as ethylene, propyleneand butene, alkyl esters of unsaturated carboxylic acids, such as methylacrylate, ethyl acrylate, methyl methacrylate, hydroxy derivativesthereof, such as 2-hydroxyethyl methacrylate, unsaturated aromaticcompounds, such as styrene, methyl styrene, vinyl styrene, andheterocyclic compounds, such as vinyl pyrrolidone, may be used ascomonomers. Preferred comonomers are acrylic acid, methacrylic acid andvinyl pyrrolidone.

The cationic polymers described above may be used in quantities of 0.1%by weight to 30% by weight, based on the rinse aid.

The present invention also relates to rinse aids for dishwashingmachines containing

a) 0.1% by weight to 30% by weight of cationic polymers selected fromcationic polymers of copolymers of monomers, such as trialkyl ammoniumalkyl (meth)acrylate or acrylamide; dialkyl diallyl diammonium salts;polymer-analog reaction products of ethers or esters of polysaccharidescontaining ammonium side groups, more particularly guar, cellulose andstarch derivatives; polyadducts of ethylene oxide containing ammoniumgroups; quaternary ethylene imine polymers and polyesters and polyamidescontaining quaternary side groups,

b) 0.5 to 30% by weight of organic carboxylic acids,

c) 0.5 to 30% by weight of nonionic surfactants selected from the groupof end-capped and OH-terminated fatty alcohol polypropyleneglycol/polyethylene glycol ethers, alkyl polyglycosides, C₆₋₂₂ fattyacid-N-alkyl polyhydroxyalkylamides, C₆₋₂₂ fatty acid alkanolamides,C₆₋₂₂ fatty acid-N-alkyl polyhydroxyalkyl amides, fatty alkyl amineoxides and mixtures thereof and

d) 10% by weight to 98.1% by weight of water.

Water-soluble homopolymers or copolymers containing monomer unitscorresponding to formula I or II are preferably used as the cationicpolymers.

Suitable organic carboxylic acids are, for example, aliphatic hydroxydi-and tri-carboxylic acids, such as malic acid (monohydroxysuccinic acid),tartaric acid (dihydroxysuccinic acid); saturated aliphatic dicarboxylicacids, such as oxalic acid, malonic acid, succinic acid, glutaric acid,adipic acid, gluconic acid (hexane pentahydroxy-1-carboxylic acid),although water-free citric acid is preferably used. The carboxylic acidsare preferably used in quantities of about 1 to 20% by weight.

The surfactant base of the rinse aids is preferably formed by nonionicsurfactants which are preferably present in a quantity of 2 to 20% byweight. The nonionic surfactants are preferably selected from the groupof mixed ethers corresponding to formula III: ##STR4## in which R¹⁰ is alinear or branched, aliphatic alkyl and/or alkenyl group containing 8 to14 carbon atoms, R¹¹ is a linear or branched alkyl group containing 1 to4 carbon atoms or a benzyl group, a is 0 or a number of 1 to 2 and b isa number of 5 to 15, fatty alcohol polypropylene glycol/polyethyleneglycol ethers corresponding to formula IV: ##STR5## in which R¹² is alinear or branched, aliphatic alkyl and/or alkenyl group containing 8 to16 carbon atoms, c is 0 or a number of 1 to 3 and d is a number of 1 to5, and alkyl polyglycosides corresponding to formula V:

    R.sup.13 O-[G].sub.p                                       (V)

in which R¹³ is an alkyl group containing 8 to 22 carbon atoms, G is asugar unit containing 5 or 6 carbon atoms, preferably a glucose unit,and p is a number of 1 to 10.

The mixed ethers corresponding to formula III are known end-capped fattyalcohol polyglycol ethers which may be obtained by relevant methods ofpreparative organic chemistry. Fatty alcohol polyglycol ethers arepreferably reacted with alkyl halides, more particularly butyl or benzylchloride, in the presence of bases. Typical examples are mixed etherscorresponding to formula III, in which R¹⁰ is a technical C_(12/14)cocoalkyl group, a is 0, b is a number of 5 to 10 and R¹¹ is a butylgroup (Dehypon® LS-54 or LS-104, Henkel KGaA). The use ofbutyl-terminated or benzyl-terminated mixed ethers is particularlypreferred for performance-related reasons.

The fatty alcohol polypropylene/polyethylene glycol ethers correspondingto formula IV are known nonionic surfactants which are obtained byaddition of, first, propylene oxide and then ethylene oxide or ethyleneoxide alone to fatty alcohols. Typical examples are polyglycol etherscorresponding to formula IV, in which R¹² is an alkyl group containing12 to 18 carbon atoms, c is 0 or 1 and d is a number of 2 to 5 (Dehydol®LS-2, LS-4, LS-5, Henkel KGaA, Dusseldorf, FRG). Preferably, however,the fatty alcohols are only ethoxylated, i.e. c=0.

Alkyl polyglycosides (APG) corresponding to formula V are knownsubstances which may be obtained by the relevant methods of preparativeorganic chemistry. EP-A-0 301 298 and WO 90/3977 are cited asrepresentative of the extensive literature available on thesesubstances.

The alkyl polyglycosides may be derived from aldoses or ketosescontaining 5 or 6 carbon atoms, preferably glucose. Accordingly,preferred alkyl polyglycosides are alkyl polyglucosides.

The index p in general formula III indicates the degree ofoligomerization (DP degree), i.e. the distribution of mono- andoligoglycosides, and is a number of 1 to 10. Whereas p in a givencompound must always be an integer and, above all, may assume a value of1 to 6, the value p for a certain alkyl oligoglycoside is ananalytically determined calculated quantity which is generally a brokennumber. Alkyl polyglycosides with an average degree of oligomerization pof 1.1 to 3.0 are preferably used. Alkyl polyglycosides with a degree ofoligomerization below 1.7 and, more particularly, between 1.2 and 1.6are preferred from the performance point of view.

Other suitable additives are solubilizers, for example cumene sulfonate,dyes and fragrances. In one preferred embodiment, the rinse aidsaccording to the invention are characterized by the absence ofsolubilizers.

The following Examples are intended to illustrate the invention withoutlimiting it in any way.

EXAMPLES

To prepare soils, white dinner plates were immersed in a hot mix ofpotato starch and oat flakes, allowed to drain and dried at 80° C. Thecleaning performance was visually evaluated by the iodine/starchreaction, i.e. by evaluating the blue coloration of the soil remainsformed with iodine solution after cleaning.

In the dishwashing tests, clean plates were first treated with rinse aidformulations 1 to 4 identified in Table 1 (dosage: 4 ml) in the finalrinse cycle of the dishwashing machine. On completion of the final rinsecycle, the plates were soiled as described above and then cleaned with acommercial dishwashing detergent (Somat® supra, a product of HenkelKGaA, Dusseldorf, FRG) in a commercial dishwashing machine.

Production of the Cationic Polymer Used

3.2 g of azo-biscyanopentanoic acid, which had been dissolved in 160 gof water in the presence of 4.3 g of 12.5% aqueous ammonia, were addedto 1600 g of a 50% solution of methacrylamidopropyl trimethyl ammoniumchloride in water and 1440 g of demineralized water.

The mixture was heated to 70° C. and left at that temperature for 30minutes. It was then left to react for another hour at 80° C.

The polymer solution obtained was clear and pale yellow at roomtemperature and had a Brookfield viscosity of 600 mPas.

                  TABLE 1                                                         ______________________________________                                                     1      2       3        4                                        ______________________________________                                        C.sub.12/14 cocofatty alcohol.5EO                                                            15.0     15.0    --     --                                       butyl ether.sup.1                                                             C.sub.12/14 cocofatty alcohol.10EO --   --  9.0    9.0                        butyl ether.sup.2                                                             C.sub.12/14 cocofatty alcohol.4EO  --     --     5.0    5.0                   adduct.sup.3                                                                  Cationic polymer                10        --     10     --                    Citric acid, water-free                 3.0  3.0   3.0    3.0                 Na cumene sulfonate                     5.0      7.0   4.0    7.0                                                   Perfume oil                                                                        0.5      0.5   0.5    0.5                                                Demineralized water       to 100                                             o 100  to 100 to 100                   ______________________________________                                         .sup.1 Dehypon ® LS54 (a product of Henkel KGaA, Dusseldorf, FRG)         .sup.2 Dehypon ® LS104 (a product of Henkel KGaA, Dusseldorf, FRG)        .sup.3 Dehydol ® LS4 (a product of Henkel KGaA, Dusseldorf, FRG)     

Cleaning performance was then evaluated on a scale of 0 to 10 where 0=nocleaning and 10=complete cleaning.

Cleaning performance was evaluated for starch and oat flakes at watertemperatures of 55° C. and 65° C. The results are set out in Table 2.

                  TABLE 2                                                         ______________________________________                                                      Potato starch Oat flakes                                                      A    B        A      B                                          ______________________________________                                        Example 1       8.3    8.2      7.0  7.0                                        Example 2 (comparison)   7.8    7.2    3.8     5                              Example 3                8.0    8.5    7.0    7.5                             Example 4 (comparison)   7.5    7.0     4     4.5                           ______________________________________                                    

A: 55° C., 20 g detergent, softened water

B: 65° C., 30 g detergent, hard water (14-16° dH)

The Examples clearly show that the use of the cationic polymers in rinseaids for machine dishwashing leads to an improvement in the removal offirmly adhering soils, such as oat flakes and other starch deposits.

What is claimed is:
 1. A rinse aid composition for use in a dishwashingmachine wherein said rinse aid composition provides improvedproteinaceous soil-removing properties to soiled dishware, saidcomposition comprising(a) 0.1% to 30% by weight of a cationic polymercontaining 40-100 mole % of monomer units corresponding to formula I:##STR6## in which R¹ is hydrogen or a methyl group,R², R³ and R⁴ are thesame or different and represent hydrogen or a C₁₋₈ alk(en)yl group, R⁸is a linear, cyclic or branched alkylene group containing 2 to 8 carbonatoms, and X represents a monofunctional anion or the 1/m part of anm-functional anion, (b) 0.5% to 30% by weight of an aliphatic di- ortricarboxylic acid, (c) 0.5% to 30% by weight of nonionic surfactantsselected from the group consisting of end-capped and OH-terminated fattyalcohol polypropylene glycol/polyethylene glycol ethers, alkylpolyglycosides, C₆₋₂₂ fatty acid-N-alkyl polyhydroxyalkylamides, C₆₋₂₂fatty acid alkanolamides, C₆₋₂₂ fatty acid-N-alkyl polyhydroxyalkylamides, fatty alkyl amine oxides and mixtures thereof, and (d) 10% byweight to 98.1% by weight of water, based on the weight of said rinseaid composition; and (e) a solubilizer comprising cumene sulfonate or analkali metal salt thereof.
 2. A rinse aid composition as in claim 1wherein said organic carboxylic acid comprises citric acid.
 3. A rinseaid composition as in claim 1 wherein said nonionic surfactants areselected from the group corresponding to formula III: ##STR7## in whichR¹⁰ is a linear or branched, aliphatic alkyl or alkenyl group containing8 to 14 carbon atoms, R¹¹ is a linear or branched alkyl group containing1 to 4 carbon atoms or a benzyl group, a is 0 or a number of 1 to 2 andb is a number of 5 to 15, fatty alcohol polypropyleneglycol/polyethylene glycol ethers corresponding to formula IV: ##STR8##in which R¹² is a linear or branched, aliphatic alkyl or alkenyl groupcontaining 8 to 16 carbon atoms, c is 0 or a number of 1 to 3 and d is anumber of 1 to 5, and alkyl polyglycosides corresponding to formula V:

    R.sup.13 O-G.sub.p                                         (V)

in which R¹³ is an alkyl group containing 8 to 22 carbon atoms, G is asugar unit containing 5 or 6 carbon atoms, and p is a number of 1 to 10.